Alert archive / California / Areal Flood Warnings in 2017

Areal Flood Warning 39, NWS San Francisco Bay Area, CA

February 20, 2017Santa Clara County, California

NWS San Francisco Bay Area, CA issued this areal flood warning at Feb 20, 2017, 11:38 PM PST for Santa Clara County, California. It was in force for 12 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Feb 20, 2017, 11:38 PM PST (07:38 UTC)
Expired
Feb 21, 2017, 11:30 AM PST
In force
12 hr
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

County Santa Clara County, CA

The radar

The San Francisco radar (KMUX), 20 km from the middle of the area, began a volume at 07:40 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Oakland, CA (KOAK), launched 00:00Z, 7.6 hours before the alert went out and 71 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Oakland, CA at 00:00Z on 2017-02-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 00:00Z on 2017-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 111 square meters per square second.1939587897117136156Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
521 m above ground
0-6 km bulk shear
99 kt
0-1 km storm-relative helicity
111 m²/s²
0-3 km storm-relative helicity
565 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS San Francisco Bay Area, CA wrote its last area forecast discussion before this areal flood warning went out at Feb 20, 10:29 PM PST, 1 hour 9 minutes earlier.

Area forecast discussion, Feb 20, 10:29 PM PST, 1 hour 9 minutes before
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In the hours before

Local storm report, Feb 20, 8:58 PM PST, 2 hours 40 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
858 PM PST MON FEB 20 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0829 PM     FLOOD            5 S MONTEREY            36.53N 121.88W
02/20/2017                   MONTEREY           CA   DEPT OF HIGHWAYS

            ROADWAY FLOODING ON QUAIL MEADOWS DR IN CARMEL VALLEY.
            LARGE SECTION OF ROADWAY FLOODED, VEHICLES SLIDING.

&&

WPI
Local storm report, Feb 20, 9:11 PM PST, 2 hours 27 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
911 PM PST MON FEB 20 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0829 PM     FLOOD            8 E GILROY              37.01N 121.43W
02/20/2017                   SANTA CLARA        CA   DEPT OF HIGHWAYS

            ROADWAY FLOODING ON HIGHWAY 152 WESTBOUND AT CASA DE
            FRUITA

&&

WPI
Local storm report, Feb 20, 9:13 PM PST, 2 hours 25 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
913 PM PST MON FEB 20 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0829 PM     FLOOD            2 S CAMPBELL            37.25N 121.96W
02/20/2017                   SANTA CLARA        CA   DEPT OF HIGHWAYS

            LARK AVE ONRAMP TO SOUTHBOUND HIGHWAY 17 FLOODED

&&

WPI
Local storm report, Feb 20, 9:29 PM PST, 2 hours 9 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
929 PM PST MON FEB 20 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0829 PM     FLOOD            3 ESE ANTIOCH           37.98N 121.74W
02/20/2017                   CONTRA COSTA       CA   DEPT OF HIGHWAYS

            LAUREL ROAD EASTBOUND ONRAMP TO HIGHWAY 4 FLOODED

0829 PM     DEBRIS FLOW      6 SW CUPERTINO          37.26N 122.12W
02/20/2017                   SANTA CRUZ         CA   DEPT OF HIGHWAYS

            MUD/DIRT/ROCK ON HIGHWAY 35 AT HIGHWAY 9 BOTH DIRECTIONS
            BLOCKED

0829 PM     DEBRIS FLOW      4 SW LOS GATOS          37.19N 122.01W
02/20/2017                   SANTA CLARA        CA   COUNTY OFFICIAL

            BLACK ROAD IS CLOSED ABOVE GIST ROAD DUE TO LANDSLIDE
            WITH TREE AND POWER LINES DOWN

0829 PM     DEBRIS FLOW      2 S LOS GATOS           37.20N 121.96W
02/20/2017                   SANTA CLARA        CA   COUNTY OFFICIAL

            SODA SPRINGS ROAD CLOSED ABOVE ALMA BRIDGE ROAD DUE TO
            LANDSLIDE

0829 PM     FLOOD            SAN JOSE                37.30N 121.85W
02/20/2017                   SANTA CLARA        CA   DEPT OF HIGHWAYS

            ROADWAY FLOODING INTERSTATE 680 NORTHBOUND SCOTT CREEK RD
            OFFRAMP

&&

WPI
Local storm report, Feb 20, 10:11 PM PST, 1 hour 27 minutes before
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Local storm report, Feb 20, 10:50 PM PST, 48 minutes before
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      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
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        Please try again in a few minutes.
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The office that day

Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 20, 4:13 PM PSTFlash Flood WarningMTRSan Benito, Santa Clara6 hr
Feb 20, 4:34 PM PSTFlash Flood WarningMTRAlameda116 min
Feb 20, 5:02 PM PSTRiver Flood WarningMTRMonterey24 hr
Feb 20, 5:03 PM PSTFlash Flood WarningMTRSanta Clara87 min
Feb 20, 5:29 PM PSTFlash Flood WarningMTRSan Mateo2 hr
Feb 20, 6:02 PM PSTFlash Flood WarningMTRSanta Cruz4 hr
Feb 20, 6:03 PM PSTAreal Flood AdvisoryMTRSan Mateo4 hr
Feb 20, 6:18 PM PSTAreal Flood AdvisoryMTRMonterey12 hr
Feb 20, 6:36 PM PSTFlash Flood WarningMTRAlameda4 hr
Feb 20, 6:54 PM PSTFlash Flood WarningMTRAlameda3 hr
Feb 20, 7:17 PM PSTFlash Flood WarningMTRSan Mateo3 hr
Feb 20, 9:15 PM PSTAreal Flood WarningMTRSanta Clara8 hr
Feb 20, 10:00 PM PSTFlash Flood WarningMTRSanta Cruz4 hr
Feb 20, 10:01 PM PSTFlash Flood WarningMTRAlameda3 hr
Feb 20, 10:15 PM PSTFlash Flood WarningMTRSan Mateo3 hr
Feb 20, 10:16 PM PSTAreal Flood WarningMTRSan Benito, Santa Clara12 hr
Feb 20, 10:34 PM PSTAreal Flood AdvisoryMTRAlameda12 hr
Feb 20, 10:42 PM PSTAreal Flood WarningMTRAlameda12 hr
Feb 21, 12:14 AM PSTAreal Flood WarningMTRMonterey12 hr
Feb 21, 1:09 AM PSTAreal Flood WarningMTRSan Mateo6 hr
Feb 21, 5:38 AM PSTAreal Flood WarningMTRSan Benito, Santa Clara15 hr
Feb 21, 8:41 AM PSTSmall Craft Advisory for Hazardous SeasMTR12 hr
Feb 21, 11:29 AM PSTAreal Flood WarningMTRSanta Clara36 hr

Nearby

Areal Flood Warnings in California, 2017Every areal flood warning in 2017

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.